ExUnit Code Review

Quick Reference

Issue Type	Reference
Async tests, setup, describe, tags	references/exunit-patterns.md
Behavior-based mocking, expectations	references/mox-boundaries.md
Bypass, Swoosh, Oban testing	references/test-adapters.md
What to mock vs real, Ecto sandbox	references/integration-tests.md

Mock Boundary Philosophy

Mock at external boundaries:

• HTTP clients, external APIs, third-party services
• Slow resources: file system, email, job queues
• Non-deterministic: DateTime.utc_now(), :rand

DO NOT mock internal code:

• Contexts, schemas, GenServers
• Internal modules, PubSub
• Anything you wrote

Review Checklist

Test Structure

• Tests are async: true unless sharing database state
• Describe-blocks group related tests
• Setup extracts common test data
• Tests have clear arrange/act/assert structure

Mocking

• Mox used for external boundaries (HTTP, APIs)
• Behaviors defined for mockable interfaces
• No mocking of internal modules
• verify_on_exit! in setup for strict mocking

Test Adapters

• Bypass for HTTP endpoint mocking
• Swoosh.TestAdapter for email testing
• Oban.Testing for background job assertions

Database

• Ecto.Adapters.SQL.Sandbox for isolation
• Async tests don't share database state
• Fixtures/factories used consistently

Valid Patterns (Do NOT Flag)

• Mock in unit test, real in integration - Different test levels have different needs
• Not mocking database in integration tests - Database is internal
• Simple inline test data - Not everything needs factories
• Testing private functions via public API - Correct approach

Context-Sensitive Rules

Issue	Flag ONLY IF
Not async	Test actually needs shared state
Missing mock	External call exists AND no mock/bypass
Mock internal	Module being mocked is internal code

Before Submitting Findings

Use the issue format: [FILE:LINE] ISSUE_TITLE for each finding.

Load and follow review-verification-protocol before reporting any issue.